Strain-insulator for electric lines.



No. 861,149. PATENTED JULY 28, 1907,

T. VARNEY.

STRAIN INSULATOR FOR ELECTRIC LINES.

APPLICATION FILED JUNE 4, 1908.

- WITNESSES: I NVENTOR L BY! g c v AT'TORNEY [UNITED STATES PATENT- OFFICE.

THEODORE YARNEY, PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE- "ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

' s'rimm-ms LAToa Fort ELECTRIC ms.-

Specification of Letters Patent.

Patented 'July 23,1907;

- Application filed Juli! 4,1906. Serial No; 320,139.,

TInsulators for Electric Lines, of which the following is a specification.

My'invention relates to strain insulators for electric lines and it has foritsobject toprovide a device ofthis character that shall be speciallycompact and durable in construction and .capable of withstandingstrains in-" cident to the use of high g The single figure of the accompanying drawing is a sectional viewof a strain insulator constructed in accordance with my invention, and reference may now be had to this figure;

The strain insulator which is illustrated, comprises a relatively short inetal tube 1, metal end caps .and' 3 thatare screw-threaded onto the ends of the tube l,

taper bolt heads or plugs 4 and 5which are fitted into suitable holes in the end caps, and means for insulating the plugs or bolt heads from the caps The caps 2 and 3 are preferably provided with taper holes 6 and 7 andthe material-of which the caps are constructed is relatively thick, adjacent to the holes, so that the taper plugs or bolt heads-4 and 5,-which arefitted substantially into the middle oi taper tubes 8 and 9 of hard insulating material, such as micanite, may

more readily and securely be seated therein.-

The taper plugs or bolt heads 4 and 5am provided I with stems or bolts 10 and 11 which extend outwardly beyond the extremities of'thetubes 8 and 9 and are screw-threaded to engage strain loops 12 and 13. The cap 3 is provided with one or more relatiyely small holes 14, which are located between the inner surface'oi the tube land the hole 7 in which the taper plug 5 is"lo.--

cated. The tapers at either end of the assembled'structure converge outwardly so that when forces in tension are applied to the strain loops l2 and 13, thetapezfings 4 and 5 are drawn firmly into position.

. When the parts already described have been assembled, the interior of the tube 1 is filled with a suitable hot liquid. insulating compound which is poured in through the openings 14, then the entire structurebetween strain loops if and 13 is enveloped in a casing 15' of molded insulation which may be applied under heavy pressure a well known manner. The pressure applied in molding the casing in: position is tra emitted rods of substantially the same diameter as the bolt heads or plugs 4 and 5 so that the pressure may be entirely equalized inside and outside the tube 1 except fora pressure tending to separate the two bolt heads or plugs 4 and 5.

g The taper tubes'S'and 9 are made of sufficient length so that a considerable surface leakage distance is provided-betyveen the, electrically separated parts and their insulating properties are retained since the casing 15 of molded insulation completely seals them from the weather, Aiurther advantage of the strain insulator of my present invention lies in the fact that any tendency for the tapered plugs or bolt heads to become loosened orunsea' t ed when the device is suddenly'released from mechanical tension is prevented by reason of the solid mass of. insulating compound which has hardened under pressure between the inner ends of the plugs or bolt heads. I

I desire that only such limitations be imposed as are indicated inthe appended claims since variations in the scope of my invention. I claim as my invention:

1. A strain insulator comprising a metal tube, removable v end caps therefor having taper holes, taper plugs seated in said holes and having stems or bolts projecting outwardly therefrom, and means for insulating the taper plugs from the end caps.

2. A strain insulator comprising a metal tube, end caps therelorhavlng taper holes. taper plugs seated in said holes and having stems or bolts projecting outwardly therefrom, means for insulating the taper plugs from theend caps and strain loops removably attached to the stems or bolts.

3. A strain insulator comprising a metaLtube having end caps provided with taper holes, taper tuhesof insulatend caps provided with taper holes, taper tubes of in'sulut ing material seated in the holes, taper plugs seated in the taper tubes and'havlng stems extending outwardly therefrom, strain loops attached to the stems and a molded casing of insulating material which seals the conductor andpextends'trom one strain loop totheother.

5; A :strain insulator comprising a metal tube, end caps theretor having taper holes, taper plugs seated. in the holes and having stems -projecting outwardly therefrom, strain loops attached to the stems, and a molded casing of "insulating material which seals the conductor and extends tube, end caps screw-threaded thereon and having outwardly tapering.

holes, taper tubes of insulating material seated in the holes, bolts projecting from the tubes, and strain loops" screw-threadetl thereon and having outwardly taperingholes, taper tubes of insulating material seated in the holes, bolts projecting from the tubes, strain loops attached to the ends of the bolts, and a casing otj'moldcd insulation that seals the structure and extends from one strain loop to the other.

9. Astrain insulator comprising a metal tube, end caps therefor having taper holes, taper plugs seated in the holes and having stems projecting outwardly therefrom, strain loops attached to the stems, an insulating compound which fills the space in the metal tube between the plugs, and a molded casing of insulating material which seals the structure and extends from one strain loop to the other.

10. A strain insulator comprising a metal tube having end caps provided with taper holes, taper tubes of insulating material seated in the holes, taper plugs seated in the taper tubes and having stems extending outwardly therefrom, strain loops attached to the stems, an insulating and having stems projecting outwardly therefrom, strain loops attached to the stems, an insulating medium within the tube which exerts a pressure tending to separate the plugs, and a molded casing of insulating material which seals the structure and extends from one strain loop to the other.

In testimony whereof, I have hereunto subscribed my name this 31st day of May, 1906.

, THEODORE VARNEY. Witnesses:

ARTHUR J. SWEET, 

